CONDUCTIVE ELASTOMERIC EXTENSOMETER

• US 3,820,529 A
• Filed: 11/07/1972
• Issued: 06/28/1974
• Est. Priority Date: 11/07/1972
• Status: Expired due to Term

• Current Assignee: Gause R, Glenn C
• Original Assignee: Gause R, Glenn C
• Inventors: GAUSE R, GLENN C
• Application Number:
  US05/304,430
• Time in Patent Office: 598 Days
• US Class Current: 600/595
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion

Abstract

An extensometer for measuring surface area changes of the human body caused by expansion and contraction of the body comprising a relatively thin and wide strain responsive conductive elastomeric band adapted for application to a part of the body, such as around a limb or the trunk of the body. The elastomeric band is incorporated as a resistor in a balanced bridge circuit. Expansion or contraction of the portion of the body on which the elastomeric band is applied causes a change in the resistance of the band and a resultant imbalance of the bridge circuit generating an output that is fed into an amplifier. The output of the amplifier in volts is suitable for providing the desired reading through a recorder, oscilloscope or voltmeter.

Claims

1. A device for measuring expansion and contraction of a surface comprising:

a conductive elastomeric band having ends and adapted for application around said surface;

means for restraining said band in contact with said surface whereby said band will expand and contract as said surface expands and contracts;

means for detecting changes in electrical resistance of said band caused by expansion and contraction thereof on said surface;

said means for restraining said band including quick-release latch means for latching the ends of said band;

said latch means comprising a phenolic body having a plurality of slots therein, the surfaces of said slots comprising an electrically conductive metal;

at least one end of said band being secured to a metallic pin, said pin being shaped to fit firmly in said slots.

2. A device as in claim 1 wherein said elastomeric band comprises 400 parts silicon elastomer to 200 parts conductive carbon black;

means for restraining said band on said surface whereby said band will expand and contract as said surface expands and contracts;

means for detecting changes in electrical resistance of said band caused by expansion and contraction thereof on said surface;

the electrical resistance of said band ranging from 12,000 ohms to 18,000 ohms per foot when said band is relaxed and ranging from 24,000 ohms to 32,000 ohms per foot when said band is elongated by 1 inch per foot;

said means for restraining said band including quick-release latch means for latching the ends of said band.

3. The invention as defined in claim 1 wherein said latch includes means for permitting rapid adjustment in length of said band, said adjustment means including a pair of rollers for clamping portions of said band together.